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Answer: Use a figure for a single number of 10 or more. Spell out a number less than 10 within a sentence, except as indicated in rules 12.5 and 12.9.

GPO rules

• Exception: the first word of the sentence is not a figure.
• If a sentence has 2 or more numbers and 1 of them is 10 or larger, use figures for each number: "15 major commodities (9 metal and 6 nonmetal)."
• Units of measurement and time are expressed in figures, even under 10: "6 years old."

• Percentage: 12 percent; 25.5 percent.

Digital.gov (differs on percent and headlines)

• Write out all numbers under 10, and use numbers with the percent symbol (7%).
• In headlines, use numerals; also use numerals for ordinals, such as 2nd and 9th.

See also

• plain-numbers-readers-use
• plain-dates-and-times-house-style

Claims

• id: C1 claim: GPO uses a figure for a single number of 10 or more. source: S1 evidence: "A figure is used for a single number of 10 or more"

• id: C2 claim: GPO spells out numbers under 10 within a sentence, with exceptions. source: S1 evidence: "a number less than 10 is spelled out within a sentence."

• id: C3 claim: GPO spells out percent after figures. source: S1 evidence: "12 percent; 25.5 percent; 0.5 percent"

• id: C4 claim: Digital.gov writes out numbers under 10. source: S2 evidence: "Write out all numbers under 10."

Sources

• [S1] GPO Style Manual (2016), Chapter 12: Numerals. U.S. Government Publishing Office (govinfo). https://www.govinfo.gov/content/pkg/GPO-STYLEMANUAL-2016/pdf/GPO-STYLEMANUAL-2016-14.pdf . License: US government work, public domain. Accessed 2026-11-09.

• [S2] Digital.gov style guide. Digital.gov (GSA). https://digital.gov/style-guide/ . License: US government work, public domain. Accessed 2026-11-09.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted). Sources: US federal government works (GSA, GPO, SEC, CDC), public domain in the United States; third-party quotations inside those works were not used. Text was condensed and changed from the originals.

@misc{iil_note_nx779ffr,
  author = {{iinventedlight}},
  title = {{Numerals or words: figures for 10 and up, words under 10}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-09},
  url = {https://iinventedlight.com/library/notes/plain-numerals-vs-words/},
  note = {Permanent ID iil:note:nx779ffr. License: CC-BY-4.0.},
}

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